No abstract

SUMMAR Y Sleep bruxism (SB) subjects show a higher incidence of rhythmic masticatory muscle activity (RMMA) than control subjects. RMMA is associated with sleep microarousals. This study aims to: (i) assess RMMA/SB episodes in relation to sleep cycles; (ii) establish if RMMA/SB and micro-arousals occur in relation to the slow wave activity (SWA) dynamics; (iii) analyze the association between RMMA/SB and autonomic cardiac activity across sleep cycles. Two nights of polygraphic recordings were made in three study groups (20 subjects each): moderate to high SB, low SB and control. RMMA episodes were considered to occur in clusters when several groups of RMMA or non-specific oromotor episodes were separated by less than 100 s. Correlations between sleep, RMMA/SB index and heart rate variability variables were assessed for the first four sleep cycles of each study group. Statistical analyses were done with SYSTAT and SPSS. It was observed that 75.8% of all RMMA/SB episodes occurred in clusters. Micro-arousal and SB indexes were highest during sleep cycles 2 and 3 (P < 0.001). Within each cycle, micro-arousal and RMMA/SB indexes showed an increase before each REM sleep (P £ 0.02). The cross-correlation plot for microarousal index showed positive association from 4 min preceding SB onset in the moderate to high SB subjects (P £ 0.06). The cross-correlation plot revealed that SWA decreases following SB onset (P £ 0.05). Further cross-correlation analysis revealed that a shift in sympatho-vagal balance towards increased sympathetic activity started 8 min preceding SB onset (P £ 0.03). In moderate to severe SB subjects, a clear increase in sympathetic activity precedes SB onset.

Sleep-related bruxism (SB) and wake-time tooth clenching (TC) have been associated with temporomandibular disorders (TMDs), headache, and sleep and behavioral complaints. This study aimed to assess the prevalence and risk factors of these signs and symptoms in a 7- to 17-yr-old population (n = 604) seeking orthodontic treatment. Data were collected by questionnaire and by a clinical examination assessing craniofacial morphology and dental status. Sleep-related bruxism was reported by 15% of the population and TC was reported by 12.4%. The SB group (n = 58) was mainly composed of children (67.3% were ≤12 yr of age) and the TC group (n = 42) was mainly composed of adolescents (78.6% were ≥13 yr of age). The craniofacial morphology of over 60% of SB subjects was dental class II and 28.1% were a brachyfacial type. Compared with controls (n = 220), SB subjects were more at risk of experiencing jaw muscle fatigue [adjusted OR (AOR) = 10.5], headache (AOR = 4.3), and loud breathing during sleep (AOR = 3.1). Compared with controls, TC subjects reported more temporomandibular joint clicking (AOR = 5), jaw muscle fatigue (AOR = 13.5), and several sleep and behavioral complaints. Sleep- and wake-time parafunctions are frequently associated with signs and symptoms suggestive of TMDs, and with sleep and behavioral problems. Their clinical assessment during the planning of orthodontic treatment is recommended.

No abstract

Although propranolol did not affect sleep bruxism, clonidine decreased sympathetic tone in the minute preceding the onset of sleep bruxism, thus reducing sleep bruxism by preventing the sequence of autonomic to motor activation of sleep bruxism. This further supports the role of sympathetic activity in the pathophysiology of sleep bruxism. Because morning hypotension was seen in 19% of patients, further dose-dependant research is required to assess the safety of clonidine for the management of sleep bruxism.

Study Objectives: Sleep bruxism (SB) is characterized by tooth grinding and jaw clenching during sleep. Familial factors may contribute to the occurrence of SB. This study aims are: (1) revisit the prevalence and characteristics of SB in a large cross-sectional survey and assess familial aggregation of SB, (2) assess comorbidity such as insomnia and pain, (3) compare survey data in a subset of subjects diagnosed using polysomnography research criteria. Methods: A sample of 6,357 individuals from the general population in Quebec, Canada, undertook an online survey to assess the prevalence of SB, comorbidities, and familial aggregation. Data on familial aggregation were compared to 111 SB subjects diagnosed using polysomnography. Results: Regularly occurring SB was reported by 8.6% of the general population, decreases with age, without any gender difference. SB awareness is concomitant with complaints of difficulties maintaining sleep in 47.6% of the cases. A third of SB positive probands reported pain. A 2.5 risk ratio of having a first-degree family member with SB was found in SB positive probands. The risk of reporting SB in first-degree family ranges from 1.4 to 2.9 with increasing severity of reported SB. Polysomnographic data shows that 37% of SB subjects had at least one first-degree relative with reported SB with a relative risk ratio of 4.625. Conclusions: Our results support the heritability of SB-tooth grinding and that sleep quality and pain are concomitant in a significant number of SB subjects.

To our knowledge, the large spectrum of sleep motor activities (SMA) present in the head and neck region has not yet been systematically estimated in normal and sleep bruxism (SB) subjects. We hypothesized that in the absence of audio-video signal recordings, normal and SB subjects would present a high level of SMA that might confound the scoring specificity of SB. A retrospective analysis of several SMA, including oro-facial activities (OFA) and rhythmic masticatory muscle activities (RMMA), was made from polygraphic and audio-video recordings of 21 normal subjects and 25 SB patients. Sleep motor activities were scored, blind to subject status, from the second night of sleep recordings. Discrimination of OFA included the following types of activities: lip sucking, head movements, chewing-like movements, swallowing, head rubbing and scratching, eye opening and blinking. These were differentiated from RMMA and tooth grinding. The frequency of SMA per hour of sleep was lower in normal subjects in comparison with SB patients (P < 0.001). Up to 85% of all SMA in normal subjects were related to OFA while 30% of SMA in SB patients were related to OFA scoring (P < 0.001). The frequency of RMMA was seven times higher in SB patients than in normal subjects (P < 0.001). Several SMA can be observed in normal and SB subjects. In the absence of audio-video signal recordings, the discrimination of various types of OFA is difficult to achieve and may lead to erroneous estimation of SB-related activities.

A recent report from the European Sleep Research Society's task force "Beyond AHI" discussed an issue that has been a long-term subject of debate -what are the best metrics for obstructive sleep apnoea (OSA) diagnosis and treatment outcome assessments? In a similar way, sleep bruxism (SB) metrics have also been a recurrent issue for >30 years and there is still uncertainty in dentistry regarding their optimisation and clinical relevance. SB can occur alone or with comorbidities such as OSA, gastroesophageal reflux disorder, insomnia, headache, orofacial pain, periodic limb movement, rapid eye movement behaviour disorder, and sleep epilepsy. Classically, the diagnosis of SB is based on the patient's dental and medical history and clinical manifestations; electromyography is used in research and for complex cases.